Martin was released by the Tampa Bay Buccaneers in February after six seasons with the team. He was named to the Pro Bowl twice but ran for a career-low 406 yards and last season and averaged 2.9 yards per carry the last two years.

Gruden said at the NFL scouting combine that he was "counting on" Marshawn Lynch to return as the team's starter. Lynch ran for 891 yards last season, his first in Oakland.

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